Acylated derivatives of pyrazofurin and process for their preparation

Abstract

A process for preparing new compounds which are N- and O-acylates of pyrazofurin comprises first selective mono-N-acylation under non-basic conditions in an organic solvent. The mono-N-acylate so formed is further acylated under mild basic conditions to provide a tetra-acylated or penta-acylated pyrazofurin derivative, depending upon the duration of reaction. Mild solvolysis of either a tetra-acylate or a penta-acylate provides a tri-acylated pyrazofurin derivative. In the presence of a strong base, the mono-N-acylate is further acylated to provide different tetra-acylates or penta-acylates of pyrazofurin, again depending upon the duration of reaction. Pyrazofurin acylates are useful as antiviral, antipsoriatic, and antifungal agents, as well as intermediates for new C-nucleosides.

I claim: 
     
       1. The compound having the formula ##SPC3## wherein:   R 1 , r 2 , r 3 , and R 5  independently are hydrogen or C 1  -C 6  alkanoyl;   R 4  is hydrogen, C 1  -C 6  alkanoyl, palmitoyl, benzoyl, or adamantoyl;   with the limitations that at least one of R 1 , R 2 , R 3 , R 4 , or R 5  is a group other than hydrogen, that R 2  is alkanoyl only when R 1  is alkanoyl, that R 3  is alkanoyl only when R 4  is alkanoyl, and that R 5  is alkanoyl only when R 3  and R 4  are both alkanoyl.   
     
     
       2. The compound of the formula ##SPC4## wherein R 1  is C 1  -C 6  alkanoyl.   
     
     
       3. The compound of claim 2, wherein R 1  is acetyl. 
     
     
       4. The compound of claim 2, wherein R 1  is n-butyryl. 
     
     
       5. The compound of claim 1, wherein R 1 , R 3 , and R 4  are C 1  -C 6  alkanoyl and R 2  and R 5  are hydrogen. 
     
     
       6. The compound of claim 5, wherein R 1 , R 3 , and R 4  are the same. 
     
     
       7. The compound of claim 6, wherein R 1 , R 3 , and R 4  are acetyl. 
     
     
       8. The compound of claim 6, wherein R 1 , R 3 , and R 4  are n-butyryl. 
     
     
       9. The compound o claim 1, wherein R 3  and R 4  are C 1  -C 6  alkanoyl, and R 1 , R 2  and R 5  are hydrogen. 
     
     
       10. The compound of claim 9, wherein R 3  and R 4  are the same. 
     
     
       11. The compound of claim 1, wherein R 1 , R 2 , R 3 , and R 4  are C 1  -C 6  alkanoyl, and R 5  is hydrogen. 
     
     
       12. The compound of claim 11, wherein R 1 , R 2 , R 3 , and R 4  are the same C 1  -C 6  alkanoyl group. 
     
     
       13. The compound of claim 1, wherein R 3 , R 4 , and R 5  are C 1  -C 6  alkanoyl and R 1  and R 2  are hydrogen. 
     
     
       14. The compound of claim 13, wherein R 3 , R 4  and R 5  are the same. 
     
     
       15. The compound of claim 14, wherein R 3 , R 4 , and R 5  are acetyl groups. 
     
     
       16. The compound of claim 14, wherein R 3 , R 4 , and R 5  are n-butyryl groups. 
     
     
       17. The compound of claim 1, wherein R 1 , R 3 , R 4 , and R 5  are C 1  -C 6  alkanoyl, and R 2  is hydrogen. 
     
     
       18. The compound of claim 17, wherein R 1 , R 3 , R 4 , and R 5  are the same alkanoyl group. 
     
     
       19. The compound of claim 18, wherein R 1 , R 3 , R 4 , and R 5  are acetyl. 
     
     
       20. The compound of claim 18, wherein R 1 , R 3 , R 4 , and R 5  are n-butyryl. 
     
     
       21. The compound of claim 1, wherein R 1 , R 2 , R 3  and R 5  are hydrogen.